ELR Citation: 55 ELR 20052
No(s). 23-9503 (10th Cir. Apr 28, 2025)

The Tenth Circuit granted in part and denied in part an environmental group's petition to review EPA approval of Colorado's 2019 SIP revisions. The group argued the revision to the permit requirement for new emission sources prevented regulators from blocking construction when a new source would generate excessive emissions, and that the addition of language to the definition of "commencement of operations," a key threshold to evaluate compliance, allowed regulators to disregard emissions during drilling, fracking, and well completion. The court concluded the group did not show an effect from the revised permit requirement, but that EPA acted arbitrarily and capriciously by failing to address potential emissions during drilling, fracking, and well completion. It remanded to EPA for further explanation of the decision to approve the definition.